From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: Terrible performance of sequential O_DIRECT 4k writes in SAN environment. ~3 times slower then Solars 10 with the same HBA/Storage. Date: Mon, 20 Jan 2014 05:58:55 -0800 Message-ID: <20140120135855.GA26280@infradead.org> References: <20140106201032.GA13491@quack.suse.cz> <20140107155830.GA28395@infradead.org> <20140108140307.GA588@infradead.org> <20140115220721.GY3469@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20140115220721.GY3469@dastard> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: Jan Kara , linux-scsi , Gluk , Linux Kernel Mailing List , xfs@oss.sgi.com, Christoph Hellwig , Sergey Meirovich List-Id: linux-scsi@vger.kernel.org On Thu, Jan 16, 2014 at 09:07:21AM +1100, Dave Chinner wrote: > Yes, I think it can be done relatively simply. We'd have to change > the code in xfs_file_aio_write_checks() to check whether EOF zeroing > was required rather than always taking an exclusive lock (for block > aligned IO at EOF sub-block zeroing isn't required), That's not even required for supporting aio appends, just a further optimization for it. > and then we'd > have to modify the direct IO code to set the is_async flag > appropriately. We'd probably need a new flag to say tell the DIO > code that AIO beyond EOF is OK, but that isn't hard to do.... Yep, need a flag to allow appending writes and then defer them. > Christoph, are you going to get any time to look at doing this in > the next few days? I'll probably need at least another week before I can get to it. If you wanna pick it up before than feel free. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs